Issue 57

K. Benyahi et alii, Frattura ed Integrità Strutturale, 57 (2021) 195-222; DOI: 10.3221/IGF-ESIS.57.16

The Fig. 22 presents the respective values of the variables introduced to the modeling on the reliability of the numerical model at the level of zone 02. The direction cosine of the random variables of the beam’s sections tested allows us to measure the influence of each of the design variables, which gives us information on the sensitivity of the design point and the reliability index to each standardized random variable. The few differences observed are related to the fact that the load case differs depending on the type of beam tested, and where we can generally see that their increase in absolute value induces better reliability. The results of the comparison of the deviations resulting from the mechano-reliability analysis on the various tested beams are presented in the Tab. 5 and the Fig. 21, where it is possible to observe a very good consistency numerical results compared to those provided by the experiment at the level of the different transition zones.

Figure 23: Difference in reliability indices between calculation and test.

The reliability study shows the importance of taking into account the three transition zones of the performance curve in order to appreciate the deviations of the distortion evolution curve  moy with the shear force V that may exist between calculation and testing. In fact, we can see generally from the Tab. 5 that in the phase before concrete cracking the difference is practically negligible, on the other hand a small difference in the post cracking phase (before steel yielding) and the post yielding steel phase between the calculation and the testing is observed. It can be seen from the Tab. 5 and from the Fig. 23 that the design point of the limit state function (performance function) is given by the second transition zone, they which gives the lowest reliability index. These reliability results allow us to show us the most significant area of the performance curve in estimating the design point. The limit state function (performance) obtained by the numerical model is not explicitly possible, we then proposed a technique for estimating the performance function, then we reduced ourselves to using a coupling technique by T C ONCLUSION he real constitutive laws of concrete, passive and active reinforcements were taken into account by the various models of behavior presented (Grelat, Sargin, BAEL99, BPEL99) allowing to correctly reproduce their stress strain envelope curves, and they have been implemented in order to deal with the shear loading behavior of reinforced and/or prestressed concrete beam sections, which makes it possible to best estimate their actual displacements. Thus, the model used satisfactorily describes the behavior of reinforced and/or prestressed concrete beams whether in terms of resistance or of displacement, in the different phases of the behavior (before cracking of the concrete, post cracking and before steels yielding, post steels yielding).

218